Construct Binary Search Tree from Preorder Traversal LeetCode solution in JavaScript

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var bstFromPreorder = function (preorder) {
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  let head = new TreeNode(preorder[0]);
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  for (let i = 1, curr; i < preorder.length; i++) {
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    curr = head;
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    while (1) {
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      if (preorder[i] > curr.val)
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        if (curr.right != null) {
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          curr = curr.right;
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        } else {
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          curr.right = new TreeNode(preorder[i]);
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          break;
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        }
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      else if (curr.left != null) {
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        curr = curr.left;
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      } else {
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        curr.left = new TreeNode(preorder[i]);
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        break;
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      }
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    }
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  }
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  return head;
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};